A few weeks ago, New Delhi was a very thirsty city. The monsoon was late, and the city’s water supply was low. Government tanker trucks delivering water to parched neighborhoods were bombarded by residents. The city’s air-conditioned malls, middle-class meccas from the desert heat, shut down public restrooms because there wasn’t enough water to flush. White-clad protesters took to the streets, waving empty water jugs in outrage over what has become an all-too-familiar problem in the capital every year before the monsoon.

By the middle of the month, the summer rains finally landed, pouring down on the city and giving some respite from what had been the hottest summer in India’s capital in 33 years. The urgency passed, but the fundamental vulnerability of people across India to an increasingly unpredictable weather event remains a serious cause for concern. The monsoon accounts for more than 80% of India’s annual rainfall, feeding crops and filling the nation’s reservoirs. Weak rains can mean less to eat for millions; an unexpected deluge can be destructive and deadly. In Assam state in India’s northeast, for instance, the rains came early and hard this year, causing a major river to overflow and killing nearly 130 unprepared people. At the same time, in Delhi and other parts of the country, meteorologists were wringing their hands as cloudless skies raised the specter of the 2009 drought that hit hundreds of districts across India, sparking deadly conflicts for water and another spate of tragic farmer suicides.

The monsoon has never been an easy thing to pin down. For thousands of years, the epic weather event has been changing, as regular systems like El Niño and La Niña shift things around. But now, human influence is starting to make its prediction even harder. The basic way the monsoon works is this: in the summer, when the land starts heating up, it heats the air, which then rises. Cooler air that has been hovering over the ocean then moves in to replace it, bringing water vapor that condenses, and eventually forms rain and falls over the subcontinent. But atmospheric particles created by cooking fires, vehicles and industrial pollution can throw that sequence off. Particles that gather can either have a light-reflecting or heat-sink effect, which can, for instance, kick off a premature monsoon that then, in turn, interferes with the main monsoon.

For Indian meteorologists, parsing out what is normal monsoon behavior and what comes from man-made sources is no small task. “You don’t [know] what is causing what,” says Vikram Mehta, executive director of the Indian Centre for Climate and Societal Impacts Research. Though the natural changes have been going on for thousands of years, Mehta says the man-made factors are having “a big impact.”

Being able to know the impact ahead of time is literally a matter of life and death in India. Water is obviously crucial to every part of a society, but in India, over 600 million people make a living off the land. They rely on the monsoon to replenish their water sources, and that leaves them vulnerable when the rains don’t come as expected — or arrive in a surprising way. While the first green revolution of the 1960s and ’70s, which brought new agricultural technology to India and other parts of the world, was a tremendous success in reducing global hunger, it was shortsighted in the way that it thought about water. “People didn’t think long term because the short-term problems were so serious,” says Mehta. “They just put down bore wells to draw groundwater. That has gone on now for 40 years all over the world … India is no exception.” As a result, groundwater, much of which is replenished by the monsoon, is becoming low as demand for food in an ever larger and richer India grows.

Climate scientists like Mehta are scrambling to figure out how the yearly monsoon is shifting and how that will shape the way people are able to live in the country. Earlier this year, scientists in the U.K. and India launched a three-year effort to study how climate change is impacting the monsoon in order to advise policymakers on how to deal with the changing weather in the coming years. Scientists in Norway are also collaborating with India’s Energy and Resources Institute to use a supercomputer in Delhi to fine-tune climate modeling for the monsoon. With a more intricate understanding of how the monsoon works, scientists would be able to better predict, for instance, a phenomena called monsoon breaks, or pauses in the rains that can lead to short, sudden droughts in farming areas. With better understanding about how and when to expect this kind of event, local officials could send out appropriate warnings to farmers about conserving water. “People at all levels are simply not aware of how to plan for monsoon variability,” says Mehta, whose center is working on creating a vertical program from scientist to farmer to improve both prediction and communication. “The challenges are vast, but that’s what people need.”

If he and his colleagues succeed, it could have a huge impact on millions of families — and India itself. “If it rains, the monetary policy works. Everything is all right. If it doesn’t rain, there is worry,” Reserve Bank of India Governor D. Subbarao was quoted in the Deccan Herald as saying during a lecture. “So I want you to realize that all of us are ‘chasing the monsoon.'”